Using wood ash in the garden - balancing ph.

[Susan BBPM]

A big drive for me in gardening is to do it all for free. This is more about the confidence of knowing that if I CAN'T get what I need in the future that I can continue to grow without it (so I have no qualms about big spends if they're a one off that will last). Anyway, to my question....

We have a woodburner so are producing huge amounts of wood ash. I know that this is good for the garden and contains most of the nutrients that plants need, but I also know it makes the soil very alkaline.

What are the 'rules' for using it?

For example, how much can I add to the compost heap without it causing problems?

Presumably I can dig it into brassica beds....but how much?

Presumably I can neutralize the ph levels by adding sulphur powder and or chips - but again, what ratios? And if I did this could I use it on all my beds or would it still be problematic for some crops?

It may have been on here that someone suggested using it as a weed killer - it'll raise the ph to the point where nothing can grow. But in this case - any thoughts on the risk of it spreading .... especially when garden is on a slope?

I hate the idea of putting all this woodash in the trash!!

 

[YumYum]

If you were to put the wood ash into the compost, then spread that compost over a 3 acre field, it won't have the same effect as putting that same compost pile in a 10x10 bed.

Putting the wood ash in the compost pile might make it stop working, I'm not sure, but I think I would just pile it up somewhere and then spread it out if you need it.

As far as how much it will raise the pH, it isn't the same for every spot. Look at this site. You must know your soils buffer pH to calculate accurately. That basically means the "acid buffer" for lack of better words. The site shows lime but if you click "show help" in the Lime Source Inputs section, it shows the CCE of wood ashes which you can input and play with the calculations just to give a general ideal of how much you might use in a given area.

If you use too much, then you have a ph buffer on the other end of the scale which determines how much acid it takes to lower the pH to a certain level.

 

[Susan BBPM]

If you were to put the wood ash into the compost, then spread that compost over a 3 acre field, it won't have the same effect as putting that same compost pile in a 10x10 bed.

Putting the wood ash in the compost pile might make it stop working, I'm not sure, but I think I would just pile it up somewhere and then spread it out if you need it.

As far as how much it will raise the pH, it isn't the same for every spot. Look at this site. You must know your soils buffer pH to calculate accurately. That basically means the "acid buffer" for lack of better words. The site shows lime but if you click "show help" in the Lime Source Inputs section, it shows the CCE of wood ashes which you can input and play with the calculations just to give a general ideal of how much you might use in a given area.

If you use too much, then you have a ph buffer on the other end of the scale which determines how much acid it takes to lower the pH to a certain level.

That has just wafted right over my head, but you've given me the info I need to go figure out what you mean. Thank you. This seems to be very useful info!!

 

[DirtMechanic]

So figure this idea out..Carbon, Oxygen and Hydrogen are the big 3, NPK follows.

Acidic soils have more loose Hydrogen. Power of H, or pH, and all that, if I express myself clearly enough.

Ashes have K and some P and are highly alkaline.

What do you make of it all? Too much takes a way primary nutrients? To reduce acidity is to reduce the free Hydrogen.

To reduce H is to reduce a primary nutrient. I am curious.

Is this why nothing grows on a burn scar for like 2 years and then it grows like somebody bribed this website?


lol that was a good one.

 

[Oliver Buckle]

I have a large oak tree at the end of the garden which spreads plenty of acidic leaves come Autumn, so I don't worry too much, but a ph kit is easy to use and shouldn't be expensive.

Is this why nothing grows on a burn scar for like 2 years and then it grows like somebody bribed this website?

Not quite true, we made a grid that fitted over four permanent posts in an apple orchard where prunings had been burned in a large bonfire. First year we got moss, then next year some nettles and docks, and on until it returned to grass. We couldn't measure the nutrient levels, but it started really alkaline and gradually washed out back to normal over about four years.

 

[YumYum]

Just another thought to ponder over... I water my garden with city water when needed (well water is likely about the same) so I'm adding carbonates which can make the soils pH go up over time, and it did before I realized what was happening. Someone who only lets the rain water their garden has a lower pH because rain is acidic and contains no minerals or carbonates to raise th pH. To fight this I run a little distilled white vinegar through my driplines.

 

[DirtMechanic]

I have a large oak tree at the end of the garden which spreads plenty of acidic leaves come Autumn, so I don't worry too much, but a ph kit is easy to use and shouldn't be expensive.

Not quite true, we made a grid that fitted over four permanent posts in an apple orchard where prunings had been burned in a large bonfire. First year we got moss, then next year some nettles and docks, and on until it returned to grass. We couldn't measure the nutrient levels, but it started really alkaline and gradually washed out back to normal over about four years.

Thats right, the first year nothing happens.